1. Field of the Invention
The present invention relates to a semiconductor apparatus in which vias are formed and a method of fabricating the same.
2. Description of the Related Art
With portable electronic appliances such as mobile phones, PDAs, DVCs and DSCs becoming more and more advanced in their capabilities, miniaturization and weight reduction of products have become essential for market acceptance. Accordingly, highly-integrated system LSIs for achieving these goals are demanded. Also, better ease and convenience of use are required of these electronic appliances. In this respect, high capabilities and high performance are required of LSIs used in these appliances. While the number of I/Os is increasing as a result of increasingly high integration of LSI chips, there is also a persistent requirement for miniaturization of packages themselves. In order to meet these incompatible demands, development of a semiconductor package adapted for high-density substrate mounting of semiconductor components is in serious demand. A packaging technology called chip size packaging (CSP) has been developed in a variety of forms to address these requirements. For example, the patent document No. 1 discloses a CSP technology.
In a semiconductor package fabricated using the CSP technology, a signal from a semiconductor chip is brought out via an electrode pad. Therefore, vias are formed on the electrode pad. Since the semiconductor chip is formed under the electrode pad, it is necessary to form a via without applying high heat.
It is to be noted that copper has come to be used as a material for electric connection in association with an increasingly high speed of the operation of electronic appliances. A problem with copper is that, when heat is applied to a pad electrode formed by copper, the surface of the pad electrode is oxidized. The patent document No. 1 describes an embodiment in which the top of the pad electrode is capped by an antioxidant Al pad electrode to address the above-mentioned problem.
Related document
    1. JP 2003-249498 A    2. JP 2002-110717 A